RecyclerView是否滑动到底部

(没有占满也算滑动到底部,记录这条是为了满足一些特殊的需求,如果是其他的,也可以尝试这个,上代码)

private val onScrollListener = object : RecyclerView.OnScrollListener() {
        override fun onScrolled(recyclerView : RecyclerView , dx : Int , dy : Int) {
            super.onScrolled(recyclerView , dx , dy)
            val layoutManager = recyclerView.layoutManager as LinearLayoutManager
            //得到当前显示的最后一个item的view
            val lastChildView = layoutManager.getChildAt(layoutManager.childCount - 1)
            lastChildView?.let {
                //得到lastChildView的bottom坐标值
                val lastChildBottom = lastChildView.bottom
                //得到Recyclerview的底部坐标减去底部padding值，也就是显示内容最底部的坐标
                val recyclerBottom = recyclerView.bottom - recyclerView.paddingBottom
                //判断lastChildView的bottom值跟recyclerBottom
                //如果满足则说明是真正的滑动到了底部
                if (lastChildBottom <= recyclerBottom ) {
                    bt_red_withdraw.visibility = View.VISIBLE
                }
            }
        }
    }